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Japanese stilt grass alert

Editor’s note: This article is from the archives of the MSUCrop Advisory Team Alerts. Check the label of any pesticide referenced to ensure your use is included.

You think garlic mustard is bad? Just imagine an annual grass that grows in undisturbed forests, spreads rapidly, blankets the ground and is highly flammable.

Japanese stilt grass came to the eastern United States accidentally and has been spreading rapidly into the Midwest. There are now several hundred populations in Illinois and Indiana. The only way we can keep it out of Michigan is to have lots of people looking for it, reporting it and immediately eradicating it.

Description

Stilt grass is weak-stemmed, has a sprawling habit and looks like a miniature bamboo. It grows slowly through the summer months, ultimately reaching heights of 2 to 3.5 feet. Leaves are pale green, relatively short and wide (1 to 3 inches long) and have a distinctive silvery stripe down the midrib caused by reflective hairs. Slender stalks of tiny flowers are produced in late summer (August to September). The seeds ripen soon after flowering, and the plant dies back completely by late fall. Patches of dried plants burn readily.

Look-alikes

Virginia cutgrass (Leersia virginica) looks similar and grows in forested areas. Cutgrass blooms earlier (August), has hairy nodes and does not have the silvery stripe down the midrib.

Biology and spread

Stilt grass reproduces exclusively by seed. It also spreads by rooting at stem nodes that touch the ground. Individual plants may produce 100 to 1,000 tiny seeds that fall close to the parent plant. Seed are easily carried further by water or moved in soil on shoes, camping gear and tires. Stilt grass seed remains viable in the soil for five or more years and germinates readily.

Control

This shallow-rooted grass can be pulled up any time in mid- to late summer. If flowering has already occurred, bag the plants and remove them from the area. Herbicides may also be used before flowering or to kill germinated seedlings.

This is an annual weed – producing seed the first year of an infestation. Any suspected population should be accurately identified, reported (and vouchered) and immediately eradicated. Do not allow this plant to go to seed.